445 
Scott.-—The Structure of Mesoxylon multirame. 
section (Fig. 6). The tangential section shown photographically in Fig. 6, 
though imperfectly preserved, gives a good idea of the distribution of the 
leaf-bases, which are recognized at once by the parenchymatous masses 
traversed by the bundles of the trace ; three such leaf-bases are shown; 
between them the plane of section passes through the Dictyoxylon cortex. 
In connexion with one leaf-base the axillary stele is shown. It will be 
noticed that the leaf-bases are moderately crowded, but so as to leave 
a quite appreciable cortical surface between them ; here again the structure 
is much the same as in M. poroxyloides . 
On the whole there seems to be scarcely any difference between these 
two species (apart from the probably accidental one of the presence or 
absence of axillary shoots) except in the mode of fusion of the leaf-trace 
bundles at the edge of the pith. This, however, is apparently important 
enough to justify keeping up the distinction. 
The affinity to M. Sutcliffii is also very close ; here the course of the 
bundles appears to be identical, and the chief distinction is found in the 
structure of the inner secondary wood, which in M. multirame everywhere 
has numerous layers of scalariform and spiral elements, while in M. Sutcliffii , 
‘ with the possible exception of a very few elements on its inner edge, the 
whole of the secondary xylem-ring, apart from the leaf-traces, consists of 
pitted tracheides ’ (Maslen, 1911 , p. 399). 
Other Specimens. 
A specimen received from Mr. Lomax in 1912 1 requires some special 
notice as it is in most respects the best-preserved Mesoxylon yet discovered, 
and differs in certain points from the type. Like the latter it is a coal-ball 
specimen from Shore, Littleborough. A portion about i| inches in length 
was cut into a series of 13 transverse sections (Nos. 2760-3772) and 8 longi¬ 
tudinal sections (Nos. 2773-2780) were obtained from the rest of the 
fragment. 
It is a relatively large stem, about 4*5 cm. in diameter, if complete. 
The diameter of the pith is about 19 mm., the thickness of the wood 
7-7*5 mm., that of the phloem and pericycle about 3 mm. The cortex is 
less well preserved than the other tissues, but was apparently about 3 mm. 
in thickness. The stem was thus a larger one to start with and also more 
advanced in growth than the type-specimen. The arrangement of the 
numerous leaf-traces is similar to that already described. As the stem is 
not quite complete, it was not possible to determine the phyllotaxis exactly ; 
the divergence may have been either or, more probably, §§. The 
behaviour of the leaf-traces agrees with that in the type ; the two bundles 
of the entering trace remain separate after entering the pith, and there is no 
1 Referred to a previous paper in connexion with M. poroxyloides (Seolt, 1912 , p. 1021). 
